CVE-2026-80981 (GCVE-0-2026-80981)
Vulnerability from cvelistv5
Published
2026-09-11 19:42
Modified
2026-10-19 08:46
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link() smc_llc_srv_add_link() keeps add_llc pointing into the queue entry: add_llc = &qentry->msg.add_link; smc_llc.c:1482 ... smc_llc_save_add_link_info(link_new, add_llc); smc_llc.c:1494 smc_llc_flow_qentry_del(&lgr->llc_flow_lcl); smc_llc.c:1495 ... u8 *llc_msg = smc_link_shared_v2_rxbuf(link) ? (u8 *)lgr->wr_rx_buf_v2 : (u8 *)add_llc; smc_llc.c:1504 smc_llc_save_add_link_rkeys(link, link_new, llc_msg); smc_llc.c:1506 smc_llc_flow_qentry_del() kfree()s the entry, so on a link without a shared v2 receive buffer the pointer handed to smc_llc_save_add_link_rkeys() is already freed. Before the Fixes: commit that branch always used lgr->wr_rx_buf_v2 and add_llc was not used after the free. Reproduced on an unpatched tree over rxe, with KASAN, kasan_multi_shot and a link forced to max_recv_sge == 1: the entry is freed and read by the same call, and the freeing frame is smc_llc_srv_add_link() itself. [ 2.523161] BUG: KASAN: slab-use-after-free in smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523499] Read of size 2 at addr ffff8880052194de by task kworker/0:1/11 [ 2.523789] [ 2.523862] CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 7.2.0-rc5-p0-g2c9dd296545d #35 PREEMPT(lazy) [ 2.523865] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 2.523866] Workqueue: smc_hs_wq smc_listen_work [ 2.523869] Call Trace: [ 2.523870] <TASK> [ 2.523871] dump_stack_lvl+0x53/0x70 [ 2.523872] print_report+0xd0/0x630 [ 2.523874] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 [ 2.523876] ? smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523878] kasan_report+0xce/0x100 [ 2.523879] ? smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523881] smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523883] ? smcr_buf_reg_lgr+0x2a4/0x660 [ 2.523885] smc_llc_srv_add_link+0xaa2/0x1e50 [ 2.523888] ? _printk+0xba/0xf0 [ 2.523897] ? __pfx_smc_llc_srv_add_link+0x10/0x10 [ 2.523899] ? down_write+0xb0/0x130 [ 2.523903] ? __pfx_down_write+0x10/0x10 [ 2.523905] smc_listen_work+0x489e/0x4d00 [ 2.523907] ? kmem_cache_free+0x1c6/0x3a0 [ 2.523911] ? __pfx_smc_listen_work+0x10/0x10 [ 2.523913] ? release_sock+0x148/0x1d0 [ 2.523915] ? smc_tcp_listen_work+0xb4f/0xfc0 [ 2.523917] ? _raw_spin_lock_irq+0x80/0xe0 [ 2.523918] ? __pfx__raw_spin_lock_irq+0x10/0x10 [ 2.523920] process_one_work+0x633/0x1030 [ 2.523922] ? assign_work+0x11d/0x370 [ 2.523924] worker_thread+0x45b/0xd10 [ 2.523926] ? __pfx_worker_thread+0x10/0x10 [ 2.523928] ? __pfx_worker_thread+0x10/0x10 [ 2.523929] kthread+0x2c6/0x3b0 [ 2.523931] ? recalc_sigpending+0x15c/0x1e0 [ 2.523934] ? __pfx_kthread+0x10/0x10 [ 2.523935] ret_from_fork+0x36e/0x5a0 [ 2.523937] ? __pfx_ret_from_fork+0x10/0x10 [ 2.523938] ? __switch_to+0x572/0xdd0 [ 2.523943] ? __pfx_kthread+0x10/0x10 [ 2.523944] ret_from_fork_asm+0x1a/0x30 [ 2.523947] </TASK> [ 2.523948] [ 2.531253] Allocated by task 48: [ 2.531399] kasan_save_stack+0x33/0x60 [ 2.531570] kasan_save_track+0x14/0x30 [ 2.531737] __kasan_kmalloc+0x8f/0xa0 [ 2.531905] __kmalloc_cache_noprof+0x158/0x370 [ 2.532100] smc_llc_enqueue+0x72/0x560 [ 2.532268] smc_wr_rx_tasklet_fn+0x474/0xa80 [ 2.532491] tasklet_action_common+0x20f/0x8a0 [ 2.532714] handle_softirqs+0x18e/0x590 [ 2.532886] do_softirq+0x3b/0x60 [ 2.533036] __local_bh_enable_ip+0x61/0x70 [ 2.533221] __alloc_skb+0x732/0x890 [ 2.533384] rxe_init_packet+0x16b/0x4f0 [ 2.533567] prepare_ack_packet+0xb8/0x830 [ 2.533760] rxe_receiver+0x495/0x96e0 [ 2.533933] do_work+0x144/0x470 [ 2 ---truncated---
References
Impacted products
Vendor Product Version
Linux Linux Version: 27ef6a9981fe74191849966a6d5e0400a4008ab8
Version: 27ef6a9981fe74191849966a6d5e0400a4008ab8
Version: 27ef6a9981fe74191849966a6d5e0400a4008ab8
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/smc/smc_llc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c52a998a223e7e84333306996edec096178d1e95",
              "status": "affected",
              "version": "27ef6a9981fe74191849966a6d5e0400a4008ab8",
              "versionType": "git"
            },
            {
              "lessThan": "adef84cc85d449ac28d2b4b4c49cf19619c56e27",
              "status": "affected",
              "version": "27ef6a9981fe74191849966a6d5e0400a4008ab8",
              "versionType": "git"
            },
            {
              "lessThan": "a42a459ef0e54cb0c4b3e43e21cb0e658e664f64",
              "status": "affected",
              "version": "27ef6a9981fe74191849966a6d5e0400a4008ab8",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/smc/smc_llc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
            },
            {
              "lessThan": "6.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link()\n\nsmc_llc_srv_add_link() keeps add_llc pointing into the queue entry:\n\n  add_llc = \u0026qentry-\u003emsg.add_link;\t\t\tsmc_llc.c:1482\n  ...\n  smc_llc_save_add_link_info(link_new, add_llc);\tsmc_llc.c:1494\n  smc_llc_flow_qentry_del(\u0026lgr-\u003ellc_flow_lcl);\t\tsmc_llc.c:1495\n  ...\n  u8 *llc_msg = smc_link_shared_v2_rxbuf(link) ?\n\t(u8 *)lgr-\u003ewr_rx_buf_v2 : (u8 *)add_llc;\tsmc_llc.c:1504\n  smc_llc_save_add_link_rkeys(link, link_new, llc_msg);\tsmc_llc.c:1506\n\nsmc_llc_flow_qentry_del() kfree()s the entry, so on a link without a shared\nv2 receive buffer the pointer handed to smc_llc_save_add_link_rkeys() is\nalready freed. Before the Fixes: commit that branch always used\nlgr-\u003ewr_rx_buf_v2 and add_llc was not used after the free.\n\nReproduced on an unpatched tree over rxe, with KASAN, kasan_multi_shot\nand a link forced to max_recv_sge == 1: the entry is freed and read by\nthe same call, and the freeing frame is smc_llc_srv_add_link() itself.\n\n  [    2.523161] BUG: KASAN: slab-use-after-free in smc_llc_save_add_link_rkeys+0x333/0x350\n  [    2.523499] Read of size 2 at addr ffff8880052194de by task kworker/0:1/11\n  [    2.523789]\n  [    2.523862] CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 7.2.0-rc5-p0-g2c9dd296545d #35 PREEMPT(lazy)\n  [    2.523865] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n  [    2.523866] Workqueue: smc_hs_wq smc_listen_work\n  [    2.523869] Call Trace:\n  [    2.523870]  \u003cTASK\u003e\n  [    2.523871]  dump_stack_lvl+0x53/0x70\n  [    2.523872]  print_report+0xd0/0x630\n  [    2.523874]  ? __pfx__raw_spin_lock_irqsave+0x10/0x10\n  [    2.523876]  ? smc_llc_save_add_link_rkeys+0x333/0x350\n  [    2.523878]  kasan_report+0xce/0x100\n  [    2.523879]  ? smc_llc_save_add_link_rkeys+0x333/0x350\n  [    2.523881]  smc_llc_save_add_link_rkeys+0x333/0x350\n  [    2.523883]  ? smcr_buf_reg_lgr+0x2a4/0x660\n  [    2.523885]  smc_llc_srv_add_link+0xaa2/0x1e50\n  [    2.523888]  ? _printk+0xba/0xf0\n  [    2.523897]  ? __pfx_smc_llc_srv_add_link+0x10/0x10\n  [    2.523899]  ? down_write+0xb0/0x130\n  [    2.523903]  ? __pfx_down_write+0x10/0x10\n  [    2.523905]  smc_listen_work+0x489e/0x4d00\n  [    2.523907]  ? kmem_cache_free+0x1c6/0x3a0\n  [    2.523911]  ? __pfx_smc_listen_work+0x10/0x10\n  [    2.523913]  ? release_sock+0x148/0x1d0\n  [    2.523915]  ? smc_tcp_listen_work+0xb4f/0xfc0\n  [    2.523917]  ? _raw_spin_lock_irq+0x80/0xe0\n  [    2.523918]  ? __pfx__raw_spin_lock_irq+0x10/0x10\n  [    2.523920]  process_one_work+0x633/0x1030\n  [    2.523922]  ? assign_work+0x11d/0x370\n  [    2.523924]  worker_thread+0x45b/0xd10\n  [    2.523926]  ? __pfx_worker_thread+0x10/0x10\n  [    2.523928]  ? __pfx_worker_thread+0x10/0x10\n  [    2.523929]  kthread+0x2c6/0x3b0\n  [    2.523931]  ? recalc_sigpending+0x15c/0x1e0\n  [    2.523934]  ? __pfx_kthread+0x10/0x10\n  [    2.523935]  ret_from_fork+0x36e/0x5a0\n  [    2.523937]  ? __pfx_ret_from_fork+0x10/0x10\n  [    2.523938]  ? __switch_to+0x572/0xdd0\n  [    2.523943]  ? __pfx_kthread+0x10/0x10\n  [    2.523944]  ret_from_fork_asm+0x1a/0x30\n  [    2.523947]  \u003c/TASK\u003e\n  [    2.523948]\n  [    2.531253] Allocated by task 48:\n  [    2.531399]  kasan_save_stack+0x33/0x60\n  [    2.531570]  kasan_save_track+0x14/0x30\n  [    2.531737]  __kasan_kmalloc+0x8f/0xa0\n  [    2.531905]  __kmalloc_cache_noprof+0x158/0x370\n  [    2.532100]  smc_llc_enqueue+0x72/0x560\n  [    2.532268]  smc_wr_rx_tasklet_fn+0x474/0xa80\n  [    2.532491]  tasklet_action_common+0x20f/0x8a0\n  [    2.532714]  handle_softirqs+0x18e/0x590\n  [    2.532886]  do_softirq+0x3b/0x60\n  [    2.533036]  __local_bh_enable_ip+0x61/0x70\n  [    2.533221]  __alloc_skb+0x732/0x890\n  [    2.533384]  rxe_init_packet+0x16b/0x4f0\n  [    2.533567]  prepare_ack_packet+0xb8/0x830\n  [    2.533760]  rxe_receiver+0x495/0x96e0\n  [    2.533933]  do_work+0x144/0x470\n  [    2\n---truncated---"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The UAF is reached from smc_listen_work() (smc_listen_rdma_finish \u2192 smcr_serv_conf_first_link \u2192 smc_llc_srv_add_link) and from LLC ADD_LINK handling; CLC is plain TCP and SMC-Rv2/RoCEv2 LLC messages are IP-routable (UDP/4791), so a remote peer that can reach an AF_SMC listener drives the path.\nAC:L - The kfree of the LLC qentry and the later read in smc_llc_save_add_link_rkeys() run sequentially in the same call with no race; on an affected SMC-Rv2 link (max_recv_sge==1, the devices this bug exists for) a connecting peer that completes first-contact and replies to ADD_LINK triggers it reliably.\nPR:N - smc_listen_work() runs the CLC/LLC handshake after TCP accept and before accept() returns to userspace; SMC authenticates nothing, and smc_create()/smc_listen() enforce no capabilities, so an unauthenticated network peer needs only reachability to the listener.\nUI:N - The listen worker is queued automatically from smc_tcp_listen_work() for inbound connections; no local user action such as mounting a filesystem or opening a file is required.\nS:U - The use-after-free corrupts kernel heap state (the kmalloc-96 LLC qentry and link-group rtoken tables) within the same host kernel security authority; it is not a VM escape, IOMMU bypass, or sandbox boundary crossing.\nC:H - The dangling add_llc pointer is a use-after-free read of a freed kmalloc-96 qentry (KASAN: slab-use-after-free in smc_llc_save_add_link_rkeys); per kernel CNA guidance a UAF of a generic slab object enables arbitrary kernel memory disclosure via heap reuse.\nI:H - smc_ib_ready_link()/smcr_buf_reg_lgr() allocate between the free and the UAF, so the object can be sprayed; smc_llc_save_add_link_rkeys() then writes those bytes into lgr-\u003ertokens, a UAF-backed write primitive usable for arbitrary kernel modification or control-flow hijack.\nA:H - KASAN reports slab-use-after-free in smc_llc_save_add_link_rkeys() from smc_listen_work on smc_hs_wq; dereferencing freed heap from that kworker oopses or panics the kernel, and a remote peer can repeat the handshake at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:46:05.740Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c52a998a223e7e84333306996edec096178d1e95"
        },
        {
          "url": "https://git.kernel.org/stable/c/adef84cc85d449ac28d2b4b4c49cf19619c56e27"
        },
        {
          "url": "https://git.kernel.org/stable/c/a42a459ef0e54cb0c4b3e43e21cb0e658e664f64"
        }
      ],
      "title": "net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80981",
    "datePublished": "2026-09-11T19:42:41.543Z",
    "dateReserved": "2026-08-26T14:34:25.811Z",
    "dateUpdated": "2026-10-19T08:46:05.740Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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